Evolutionary Studies Institute (ESI)http://hdl.handle.net/10539/13252
Wed, 09 Aug 2017 09:49:48 GMT2017-08-09T09:49:48ZThe bony labyrinth of late Permian Biarmosuchia: palaeobiology and diversity in non-mammalian Therapsidahttp://hdl.handle.net/10539/23023
The bony labyrinth of late Permian Biarmosuchia: palaeobiology and diversity in non-mammalian Therapsida
Benoit, Julien; Manger, Paul R; Fernandez, Vincent; Rubidge, Bruce S
Biarmosuchia, as the basalmost group of Therapsida (the stem group of mammals), are important for understanding mammalian
origins and evolution. Unlike other therapsid groups, the bony labyrinth of biarmosuchians has not yet been studied, despite insightful
clues that bony labyrinth morphology can provide to address palaeobiology and phylogeny of extinct animals. Here, using CT
scanning, surface reconstruction and a 3D geometric-morphometric protocol of 60 semi-landmarks on the bony labyrinth of
30 therapsids (including three Mammaliaformes), it is demonstrated that bony labyrinth morphology of biarmosuchians is very
distinctive compared to that of other therapsids. Despite the primitive nature of their cranial morphology, biarmosuchians display
highly derived traits in the structure of the bony labyrinth. The most noticeable are the presence of a long and slender canal linking the
vestibule to the fenestra vestibuli, an enlarged and dorsally expanded anterior canal, and the absence of a secondary common crus
(except for one specimen), which sets them apart from other non-mammalian therapsids. These characters provide additional support
for the monophyly of Biarmosuchia, the most recently recognized major therapsid subclade. Although implications of the derived
morphology of the biarmosuchian bony labyrinth are discussed, definitive interpretations are dependent on the discovery of
well-preserved postcranial material. It nevertheless sheds light on a previously overlooked diversity of bony labyrinth morphology
in non-mammalian therapsids.
Sat, 01 Jul 2017 00:00:00 GMThttp://hdl.handle.net/10539/230232017-07-01T00:00:00ZPalynological dating and palaeoenvironments of the M1 well, Middle Miocene, Niger Delta, Nigeriahttp://hdl.handle.net/10539/23021
Palynological dating and palaeoenvironments of the M1 well, Middle Miocene, Niger Delta, Nigeria
Durugbo, Ernest Uzodimma; Olayiwola, Moshood Adegboyega
The need to increase our knowledge of palaeo-flora is important in palaeoclimatic and palaeoenvironmental reconstruction of the
Tertiary Niger Delta as to highlight possible changes in the depositional environments over time. Hence, palynological data from the
M1well from the western Niger Delta region were employed in an attempt to reconstruct the Middle Miocene palaeoenvironment and
palaeoclimate. The detailed palynological analysis revealed diverse and abundant palynomorph assemblages. This consisted of pollen
species 60.14%, spores 25.86%, algae (Botyococcus braunii, Pediastrum sp., and Concentricytes circulus) 10.53%, miscellaneous
palynomorphs (fungal elements, diatom frustules and charred Gramineae cuticle) 2.62%, dinoflagellate cysts 0.79% and acritarchs
0.06%. The well is dated Middle Miocene based on the common occurrences of diagnostic middle Miocene Niger Delta palynomorphs.
Four informal palynofloral assemblage zones (MPAZ) I–IV were defined and correlated with major cycles of alternating dry and wet
climatic conditions. Sediments within MPAZ I and MPAZ II were assumed to have been deposited during dominantly wet periods
while MPAZ IV and III showed brief dry pulses coupled with periods of marine transgressions. The palaeoenvironment fluctuated
between nearshore and marginal marine inferred from abundant records of land-derived palynomorphs and the spotty records of the
dinoflagellate cysts Nematosphaeropsis labyrinthus, Nematosphaeropsis lemniscata and Impagidinium sp.
Sat, 01 Jul 2017 00:00:00 GMThttp://hdl.handle.net/10539/230212017-07-01T00:00:00ZProceedings of the 2017 biennial conference of the South African Society of Quaternary Researchhttp://hdl.handle.net/10539/23008
Proceedings of the 2017 biennial conference of the South African Society of Quaternary Research
Fitchett, Jennifer M.; Bamford, Marion K.
Proceedings of the 21st Biennial Conference of the South African
Society of Quaternary Research, Johannesburg, 3–7 April 2017
Sat, 01 Apr 2017 00:00:00 GMThttp://hdl.handle.net/10539/230082017-04-01T00:00:00ZA Partially Articulated Cynodont Encased in a Putative Burrow Structure from the Cynognathus Subzone Chttp://hdl.handle.net/10539/22985
A Partially Articulated Cynodont Encased in a Putative Burrow Structure from the Cynognathus Subzone C
Afonso, Nadia
A sedimentary structure containing a fossilized therapsid, and bioglyphs on the
surface morphology, was found during a field expedition to Cynognathus subzone-C in the
Eastern Cape, South Africa. A combination of surface scanning, petrographic thin sections,
bone mapping and anatomical comparison were used to determine the deposit type and
taxonomic identity of the encased therapsid, and examine the implications for biostratigraphy
and faunal assemblage of the Cynognathus Assemblage Zone. The deposit is hypothesized to
be a portion of a cynodont burrow (burrow margin) that was constructed in fluvial sediment
near a river bank. This is the first account of a burrow in subzone-C. Pattern and
directionality analysis of the bioglyphs suggest that the bioglyphs are scratch marks made by
the burrower during excavation. The scratch marks are mediolaterally narrow, with some
exhibiting indentation marks, indicating that the tracemaker had mediolaterally narrow
unguals at the distal phalanx (claws). Anomodonts and cynodonts were common burrowers
during the Triassic, however comparisons of Thrinaxodon and Lystrosaurus scratch marks to
the bioglyphs on this deposit suggests that the bioglyphs were likely constructed by a
cynodont as anomodont unguals are laterally wider, and are unable to create mediolaterally
narrow markings. The tracemaker is hypothesized to be closely related to Thrinaxodon based
on scratch mark comparison. However, bioglyph published literature is limited, and therefore
the tracemaker cannot be identified. The therapsid was identified as Diademodon based on
cranial and dental morphology. There is limited published literature on Diademodon
constructing and/or exploiting burrows, however the taphonomy suggests that the
Diademodon was near the entrance or in the tunnel of burrow nearing/during death. This is
the first account of Diademodon encased in a burrow.
Thu, 01 Oct 2015 00:00:00 GMThttp://hdl.handle.net/10539/229852015-10-01T00:00:00Z